The invention pertains to apparatus for applying thin layers to a substrate by means of the cathode sputtering process in a vacuum chamber, through which the substrate to be coated can be transported. The apparatus includes a diaphragm under the cathode to be sputtered, where the plane of the substrate extends underneath the anode. Members supported by the walls of the vacuum chamber are provided with conduits, through which a coolant and a process gas are conveyed. The conduits for the process gas are provided with openings, which are transverse to the longitudinal axis of the conduit and which allow the process gas to escape into the vacuum chamber.
U.S. Pat. No. 4,946,576 discloses cathode sputtering apparatus wherein a mechanical diaphragm is installed between the cathode to be sputtered and the anode to divide the space between the cathode and the substrate to be coated. This apparatus is equipped with several separate cooling pipes and gas pipelines to supply the system with cooling medium and process gas.
This known device suffers from the disadvantage that the cooling medium and the process gas are supplied and returned through separate, multi-component pipelines. The system is thus is highly susceptible to operating breakdowns and is also complicated to produce and maintain. The pipelines have bends, coils, screw joints, and soldered joints, which are under vacuum during the operation of the system. These conditions, under the additional influence of process-related heat, lead to hairline cracks and leaks in the pipelines. At first, these leaks merely impair the quality of the layers, by reducing, for example, the adhesive strength of the layer being applied to the substrate during the sputtering process. Subsequently, however, they lead inevitably to the total failure of the entire system, which is always associated with considerable labor and enormous cost.
To obtain a significant increase in operational reliability and thus to reduce the down times, to achieve a considerable simplification of the production and maintenance work, and thus to arrive at a significant reduction in the production and operating costs, U.S. Pat. No. 5,223,111 proposes that both the cooling medium and the process gas be conducted through conduits in a one-piece structural component in the form of a hollow member. Openings transverse to the longitudinal axis of the conduits are provided to allow the process gas to escape. The anodes and diaphragms are screwed directly to the hollow member.
In known devices of the type described above, the anodes become coated rather quickly during the sputtering process with an insulating layer, which considerably reduces their service life. The coated anodes must therefore be removed at regular intervals from the process chamber and freed of the insulating layer, for example by sandblasting, which represents a considerable interruption of the production process. Known anodes are attached to the walls of the process chamber by means of insulating bushings and Teflon strips, which project into the area of the sputtering zone. After a certain sputtering time, this arrangement leads to functional problems, because these parts are not cooled. As a result, the known anodes can be subjected to only modest thermal loads.